This is a note to let you know that I've just added the patch titled

    __bitmap_parselist: fix bug in empty string handling

to the 4.1-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     __bitmap_parselist-fix-bug-in-empty-string-handling.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From 2528a8b8f457d7432552d0e2b6f0f4046bb702f4 Mon Sep 17 00:00:00 2001
From: Chris Metcalf <[email protected]>
Date: Thu, 25 Jun 2015 15:02:08 -0700
Subject: __bitmap_parselist: fix bug in empty string handling

From: Chris Metcalf <[email protected]>

commit 2528a8b8f457d7432552d0e2b6f0f4046bb702f4 upstream.

bitmap_parselist("", &mask, nmaskbits) will erroneously set bit zero in
the mask.  The same bug is visible in cpumask_parselist() since it is
layered on top of the bitmask code, e.g.  if you boot with "isolcpus=",
you will actually end up with cpu zero isolated.

The bug was introduced in commit 4b060420a596 ("bitmap, irq: add
smp_affinity_list interface to /proc/irq") when bitmap_parselist() was
generalized to support userspace as well as kernelspace.

Fixes: 4b060420a596 ("bitmap, irq: add smp_affinity_list interface to 
/proc/irq")
Signed-off-by: Chris Metcalf <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 lib/bitmap.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -506,12 +506,12 @@ static int __bitmap_parselist(const char
        unsigned a, b;
        int c, old_c, totaldigits;
        const char __user __force *ubuf = (const char __user __force *)buf;
-       int exp_digit, in_range;
+       int at_start, in_range;
 
        totaldigits = c = 0;
        bitmap_zero(maskp, nmaskbits);
        do {
-               exp_digit = 1;
+               at_start = 1;
                in_range = 0;
                a = b = 0;
 
@@ -540,11 +540,10 @@ static int __bitmap_parselist(const char
                                break;
 
                        if (c == '-') {
-                               if (exp_digit || in_range)
+                               if (at_start || in_range)
                                        return -EINVAL;
                                b = 0;
                                in_range = 1;
-                               exp_digit = 1;
                                continue;
                        }
 
@@ -554,16 +553,18 @@ static int __bitmap_parselist(const char
                        b = b * 10 + (c - '0');
                        if (!in_range)
                                a = b;
-                       exp_digit = 0;
+                       at_start = 0;
                        totaldigits++;
                }
                if (!(a <= b))
                        return -EINVAL;
                if (b >= nmaskbits)
                        return -ERANGE;
-               while (a <= b) {
-                       set_bit(a, maskp);
-                       a++;
+               if (!at_start) {
+                       while (a <= b) {
+                               set_bit(a, maskp);
+                               a++;
+                       }
                }
        } while (buflen && c == ',');
        return 0;


Patches currently in stable-queue which might be from [email protected] are

queue-4.1/__bitmap_parselist-fix-bug-in-empty-string-handling.patch
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